Light Scattering Enhancement in Nanostructured Silver Film Composites

We experimentally investigated the extinction properties of thin silver films. The films consisted of arrays of nanoparticles deposited by pulsed laser ablation on a dielectric substrate, thus resulting in a composite system. Adopting a set of deposition parameter values, we obtained different and controlled morphologies, from isolated to increasingly clustered nanoparticles. We found that, in analogy with nanostructured particle composites, the dipolar moments of different nanoparticle clusters are coupled, giving rise to a local electromagnetic enhancement. The imaginary part of the polarizability of the system obeys scaling laws, the optical spectral dimension d(0) being 0.3.